Improve python coding style

As per check-python-files.sh, added string documentation for
files and functions.

Modified for loops to use enumerate rather than range(len(
although as the same iteration index is used for multiple
lists it does not seem quite appropriate

Signed-off-by: Joe Subbiani <joe.subbiani@arm.com>
diff --git a/tests/scripts/test_translate_ciphers_names.py b/tests/scripts/test_translate_ciphers_names.py
index f6cfa6d..c40d376 100755
--- a/tests/scripts/test_translate_ciphers_names.py
+++ b/tests/scripts/test_translate_ciphers_names.py
@@ -17,21 +17,32 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-# Purpose
-#
-# Test translate_ciphers.py by running every MBedTLS ciphersuite name
-# combination through the translate functions and comparing them to their
-# correct GNUTLS or OpenSSL counterpart.
 
-from translate_ciphers import *
+"""
+Test translate_ciphers.py by running every MBedTLS ciphersuite name
+combination through the translate functions and comparing them to their
+correct GNUTLS or OpenSSL counterpart.
+"""
+
+from translate_ciphers import translate_gnutls, translate_ossl
 
 def assert_equal(translate, original):
+    """
+    Compare the translated ciphersuite name against the original
+    On fail, print the mismatch on the screen to directly compare the
+    differences
+    """
     try:
-        assert(translate == original)
+        assert translate == original
     except AssertionError:
         print("%s\n%s\n" %(translate, original))
 
 def test_all_common():
+    """
+    Translate the MBedTLS ciphersuite names to the common OpenSSL and
+    GnuTLS ciphersite names, and compare them with the true, expected
+    corresponding OpenSSL and GnuTLS ciphersuite names
+    """
     m_ciphers = [
         "TLS-ECDHE-ECDSA-WITH-NULL-SHA",
         "TLS-ECDHE-ECDSA-WITH-3DES-EDE-CBC-SHA",
@@ -172,15 +183,20 @@
         "PSK-AES256-CBC-SHA",
     ]
 
-    for i in range(len(m_ciphers)):
+    for i, m_cipher in enumerate(m_ciphers):
 
-        g = translate_gnutls(m_ciphers[i])
+        g = translate_gnutls(m_cipher)
         assert_equal(g, g_ciphers[i])
 
-        o = translate_ossl(m_ciphers[i])
+        o = translate_ossl(m_cipher)
         assert_equal(o, o_ciphers[i])
 
 def test_mbedtls_ossl_common():
+    """
+    Translate the MBedTLS ciphersuite names to the common OpenSSL
+    ciphersite names, and compare them with the true, expected
+    corresponding OpenSSL ciphersuite name
+    """
     m_ciphers = [
         "TLS-ECDH-ECDSA-WITH-NULL-SHA",
         "TLS-ECDH-ECDSA-WITH-3DES-EDE-CBC-SHA",
@@ -250,12 +266,17 @@
         "DHE-PSK-CHACHA20-POLY1305",
     ]
 
-    for i in range(len(m_ciphers)):
+    for i, m_cipher in enumerate(m_ciphers):
 
-        o = translate_ossl(m_ciphers[i])
+        o = translate_ossl(m_cipher)
         assert_equal(o, o_ciphers[i])
 
 def test_mbedtls_gnutls_common():
+    """
+    Translate the MBedTLS ciphersuite names to the common GnuTLS
+    ciphersite names, and compare them with the true, expected
+    corresponding GnuTLS ciphersuite names
+    """
     m_ciphers = [
         "TLS-ECDHE-ECDSA-WITH-CAMELLIA-128-CBC-SHA256",
         "TLS-ECDHE-ECDSA-WITH-CAMELLIA-256-CBC-SHA384",
@@ -435,9 +456,9 @@
         "+RSA-PSK:+AES-128-GCM:+AEAD",
     ]
 
-    for i in range(len(m_ciphers)):
+    for i, m_ciphers in enumerate(m_ciphers):
 
-        g = translate_gnutls(m_ciphers[i])
+        g = translate_gnutls(m_ciphers)
         assert_equal(g, g_ciphers[i])
 
 test_all_common()
diff --git a/tests/scripts/translate_ciphers.py b/tests/scripts/translate_ciphers.py
index 2f1543c..66c878a 100755
--- a/tests/scripts/translate_ciphers.py
+++ b/tests/scripts/translate_ciphers.py
@@ -16,23 +16,27 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-#
-# Purpose
-#
-# Translate ciphersuite names in MBedTLS format to OpenSSL and GNUTLS
-# standards.
-#
-# Format and analyse strings past in via input arguments to match
-# the expected strings utilised in compat.sh.
-#
-# sys.argv[1] should be "g" or "o" for GNUTLS or OpenSSL.
-# sys.argv[2] should be a string containing one or more
-# ciphersuite names.
+
+"""
+Translate ciphersuite names in MBedTLS format to OpenSSL and GNUTLS
+standards.
+
+Format and analyse strings past in via input arguments to match
+the expected strings utilised in compat.sh.
+
+sys.argv[1] should be "g" or "o" for GNUTLS or OpenSSL.
+sys.argv[2] should be a string containing one or more ciphersuite names.
+"""
 
 import re
 import sys
 
 def translate_gnutls(m_cipher):
+    """
+    Translate m_cipher from MBedTLS ciphersuite naming convention
+    and return the GnuTLS naming convention
+    """
+
     # Remove "TLS-"
     # Replace "-WITH-" with ":+"
     # Remove "EDE"
@@ -51,13 +55,18 @@
     # Replace the last "-" with ":+"
     # Replace "GCM:+SHAxyz" with "GCM:+AEAD"
     else:
-        index=m_cipher.rindex("-")
+        index = m_cipher.rindex("-")
         m_cipher = m_cipher[:index]+":+"+m_cipher[index+1:]
         m_cipher = re.sub(r"GCM\:\+SHA\d\d\d", "GCM:+AEAD", m_cipher)
 
     return m_cipher
 
 def translate_ossl(m_cipher):
+    """
+    Translate m_cipher from MBedTLS ciphersuite naming convention
+    and return the OpenSSL naming convention
+    """
+
     # Remove "TLS-"
     # Remove "WITH"
     m_cipher = m_cipher[4:]
@@ -89,7 +98,7 @@
     # POLY1305 should not be followed by anything
     if "POLY1305" in m_cipher:
         index = m_cipher.rindex("POLY1305")
-        m_cipher=m_cipher[:index+8]
+        m_cipher = m_cipher[:index+8]
 
     # If DES is being used, Replace DHE with EDH
     if "DES" in m_cipher and "DHE" in m_cipher and "ECDHE" not in m_cipher:
@@ -101,9 +110,9 @@
     try:
         t = {"g": translate_gnutls, "o": translate_ossl}[mode]
         return " ".join(t(c) for c in ciphers.split())
-    except Exception as E:
-        if E != mode: print(E)
-        else: print("Incorrect use of argument 1, should be either \"g\" or \"o\"")
+    except (KeyError) as e:
+        print(e)
+        print("Incorrect use of argument 1, should be either \"g\" or \"o\"")
         sys.exit(1)
 
 def main():