A simpler conversion function to convert from Rosetta numbering without requiring the chain identifier.

def convert_from_rosetta(self, residue_id, to_scheme):
        '''A simpler conversion function to convert from Rosetta numbering without requiring the chain identifier.'''

        assert(type(residue_id) == types.IntType)

        # Find the chain_id associated with the residue_id
        # Scan *all* sequences without breaking out to make sure that we do not have any duplicate maps
        chain_id = None
        for c, sequence in self.rosetta_sequences.iteritems():
            for id, r in sequence:
                if r.ResidueID == residue_id:
                    assert(chain_id == None)
                    chain_id = c

        if chain_id:
            return self.convert(chain_id, residue_id, 'rosetta', to_scheme)
        else:
            return None