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/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():