Python 3: How to check if a string can be a valid variable?

Question

I have a string and want to check if it can be used as a valid variable without getting a syntax error. For example

def variableName(string):
    #if string is valid variable name:
        #return True
    #else:
        #return False

input >>> variableName("validVariable")
output >>> True
input >>> variableName("992variable")
output >>> False

I would not like to use the .isidentifier(). I want to make a function of my own.

Answer 1

The following answer is true only for "old-style" Python-2.7 identifiers;

"validVariable".isidentifier()
#True
"992variable".isidentifier()
#False

Since you changed your question after I posted the answer, consider writing a regular expression:

re.match(r"[_a-z]\w*$", yourstring,flags=re.I)