returned dictionary value is 'None' python

I have a function in a file which I am calling in a separate script (as shown below). Printing directly from the function works correctly, however when I try to return the value to the script it sends 'None'.

Any help would be appreciated. Thanks

script:

import modules.functions as f

restype = 'THR'
atomtype = 'CA'

print f.AtomType(restype,atomtype)

function: (this is the part of the function which returns the value)

def AtomType(resName,atomType):
    def threonine():
        print 'well im here'
        atoms = {'N' : 1,
                 'CA': 6,
                 'C' : 8,
                 'O' : 2,
                 'CB': 6,
                 'OG1': 1,
                 'CG2': 4, 
                 }    

            print atoms[atomType]
            return atoms[atomType]

    residues = {'ALA' : hydrophobic,
                'ARG' : arginine,
                'ASN' : asparagine,
                'ASP' : aspartate,
                'CYS' : cysteine,
                'GLN' : glutamine,
                'GLU' : glutamate,
                'GLY' : hydrophobic,
                'HIS' : histidine,
                'ILE' : hydrophobic,
                'LEU' : hydrophobic,
                'LYS' : lysine,
                'MET' : methionine,
                'PHE' : phenylalanine,
                'PRO' : proline,
                'SER' : serine,
                'THR' : threonine,
                'TRP' : tryptophan,
                'TYR' : tyrosine,
                'VAL' : hydrophobic,
                }

    residues[resName]()

and the outpu开发者_Go百科t I get is:

well im here
6
None

edit: added entire function

---

Here's a guess: AtomType calls threonine, but doesn't return its return value.