#!/usr/bin/env python

def identifierChecker():

    import string

    alphas = string.ascii_letters + '_'
    nums = string.digits
    alphanums = alphas + nums
    print 'Welcome to the Identifier Checker v1.0'
    print 'Testees must be at least 2 chars long.'
    myInput = raw_input('Identifier to test? ')

    if len(myInput) > 1:

        if myInput[0] not in alphas:
            print '''invalid: first symbol must be alphabetic'''
        else:
            for otherChar in myInput [1:]:

                if otherChar not in alphanums:
                    print '''invalid: remaining symbols must be alphanumeric'''
                    break
            else:
                print "Okay as an identifier"

In [8]: identifierChecker()
Welcome to the Identifier Checker v1.0
Testees must be at least 2 chars long.
Identifier to test? count4rer
Okay as an identifier

In [9]: identifierChecker()
Welcome to the Identifier Checker v1.0
Testees must be at least 2 chars long.
Identifier to test? 3d_effects
invalid: first symbol must be alphabetic

In [11]: identifierChecker()
Welcome to the Identifier Checker v1.0
Testees must be at least 2 chars long.
Identifier to test? 1

In [12]: