code: def add(self, obj):
          
          # base datatype components can't have more than one child
          if self.name and is_base_datatype(self.datatype, self.version) and \
                  len(self.children) >= 1:
              raise MaxChildLimitReached(self, obj, 1)
  
          return super(Field, self).add(obj)
docs: Add an instance of :class:`Component <hl7apy.core.Component>` to the list of children
  
          :param obj: an instance of :class:`Component <hl7apy.core.Component>`
  
          >>> f = Field('PID_5')
          >>> f.xpn_1 = 'EVERYMAN'
          >>> c = Component('XPN_2')
          >>> c.value = 'ADAM'
          >>> f.add(c)
          >>> print(f.to_er7())
          EVERYMAN^ADAM