docs: def _where_clause(where):
          """
          Unpack a where clause tuple and concatenate a MySQL WHERE statement.
  
          :param where: 2 or 3 part tuple containing a where_column and a where_value (optional operator)
          :return: WHERE clause statement
          """
          assert isinstance(where, tuple)
          if len(where) == 3:
              where_col, operator, where_val = where
          else:
              where_col, where_val = where
              operator = '='
          assert operator in SELECT_WHERE_OPERATORS
  
          # Concatenate WHERE clause (ex: **first_name='John'**)
          return "{0}{1}'{2}'".format(where_col, operator, where_val)