Python question

Write a function is_nneg_float() that checks if string s denotes a non- negative floating point value (not in scientific notation). This function should return True if s contains (at most) one decimal point and one or more digits (and nothing else); and False otherwise. According to this definition an integer should return True.

>>> is_nneg_float("2.15") True >>> is_nneg_float("3.") True >>> is_nneg_float(".5") True >>> is_nneg_float("123") True >>> is_nneg_float("-12") False