Python basics:

A Python identifier is a name used to identify a variable, function, class, module or other object. An identifier starts with a letter A to Z or a to z or an underscore (_) followed by zero or more letters, underscores and digits (0 to 9).

Python does not allow punctuation characters such as @, $ and % within identifiers. Python is a case sensitive programming language. Thus, Manpower and manpower are two different identifiers in Python.

Here are following identifier naming convention for Python:

• Class names start with an uppercase letter and all other identifiers with a lowercase letter.
• Starting an identifier with a single leading underscore indicates by convention that the identifier is meant to be private.
• Starting an identifier with two leading underscores indicates a strongly private identifier.
• If the identifier also ends with two trailing underscores, the identifier is a language-defined special name.One of the first caveats programmers encounter when learning Python is the fact that there are no braces to indicate blocks of code for class and function definitions or flow control. Blocks of code are denoted by line indentation, which is rigidly enforced.
  The number of spaces in the indentation is variable, but all statements within the block must be indented the same amount. Both blocks in this example are fine:try this

• #!/usr/bin/python
  
  import sys
  
  try:
    # open file stream
    file = open(file_name, "w")
  except IOError:
    print "There was an error writing to", file_name
    sys.exit()
  print "Enter '", file_finish,
  print "' When finished"
  while file_text != file_finish:
    file_text = raw_input("Enter text: ")
    if file_text == file_finish:
      # close the file
      file.close
      break
    file.write(file_text)
    file.write("\n")
  file.close()
  file_name = raw_input("Enter filename: ")
  if len(file_name) == 0:
    print "Next time please enter something"
    sys.exit()
  try:
    file = open(file_name, "r")
  except IOError:
    print "There was an error reading file"
    sys.exit()
  file_text = file.read()
  file.close()
  print file_text