Verify Signature of Functions Returned by `parser.get_functions`

[nuthanmunaiah]

Description

In resolving #40, parser.models.Function was modified to add signature field. The signature of a function is constructed by combining multiple elements in the SrcML representation of a function declaration or function definition. The (manual) verification of the function signature constructed by parser.get_functions is time intensive. As a result, the verification is not being prioritized at this point.