code: def get_foreign_key(self, name):
          
          name = self._normalize_identifier(name)
  
          if not self.has_foreign_key(name):
              raise ForeignKeyDoesNotExist(name, self._name)
  
          return self._fk_constraints[name]
docs: Returns the foreign key constraint with the given name.
  
          :param name: The constraint name
          :type name: str
  
          :rtype: ForeignKeyConstraint