code: def remove_BC(self, pores=None):
          r
          if pores is None:
              pores = self.Ps
          if 'pore.bc_value' in self.keys():
              self['pore.bc_value'][pores] = np.nan
          if 'pore.bc_rate' in self.keys():
              self['pore.bc_rate'][pores] = np.nan
docs: r"""
          Removes all boundary conditions from the specified pores
  
          Parameters
          ----------
          pores : array_like
              The pores from which boundary conditions are to be removed.  If no
              pores are specified, then BCs are removed from all pores. No error
              is thrown if the provided pores do not have any BCs assigned.