Parses a row, cell-by-cell, returning a dict of field names
        to the cleaned field values.

def parse_row(self):
        """
        Parses a row, cell-by-cell, returning a dict of field names
        to the cleaned field values.
        """
        fields = self.mapping
        for i, cell in enumerate(self.row[0:len(fields)]):
            field_name, field_type = fields[str(i)]
            parsed_cell = self.clean_cell(cell, field_type)
            self.parsed_row[field_name] = parsed_cell