code: def init_interface(field):
      '''Return a Field object defined at the vertical interfaces of the input Field object.'''
      interface_shape = np.array(field.shape); interface_shape[-1] += 1
      interfaces = np.tile(False,len(interface_shape)); interfaces[-1] = True
      interface_zero = Field(np.zeros(interface_shape), domain=field.domain, interfaces=interfaces)
      return interface_zerf init_interface(field):
      '''Return a Field object defined at the vertical interfaces of the input Field object.'''
      interface_shape = np.array(field.shape); interface_shape[-1] += 1
      interfaces = np.tile(False,len(interface_shape)); interfaces[-1] = True
      interface_zero = Field(np.zeros(interface_shape), domain=field.domain, interfaces=interfaces)
      return interface_zero
docs: Return a Field object defined at the vertical interfaces of the input Field object.