Takes in a chain identifier and protein sequence and returns a Sequence object of Residues, indexed from 1.

def from_sequence(chain, list_of_residues, sequence_type = None):
        '''Takes in a chain identifier and protein sequence and returns a Sequence object of Residues, indexed from 1.'''
        s = Sequence(sequence_type)
        count = 1
        for ResidueAA in list_of_residues:
            s.add(Residue(chain, count, ResidueAA, sequence_type))
            count += 1
        return s