docs: def get_component(self, entity, component_type, missing=MISSING):
          """Get the component of type component_type associated with entity.
  
          Long-hand for :func:`essence.Entity.get`.
  
          :param entity: entity to query
          :type entity: :class:`essence.Entity`
          :param component_type: component to add to the entity
          :type component_type: The :class:`type` of a :class:`Component` subclass
          :param missing: value to return if
          :type missing: :class:`essence.Component`
          :raises:"""
          relation = self._get_relation(component_type)
          if entity not in relation:
              if missing is MISSING:
                  raise NoSuchComponentError()
              else:
                  return missing
          return relation[entity]