code: def _isvalid(self, datatype):
          '''Checks if the given datatype is valid in meta'''
          if datatype in self.meta:
              return bool(Dap._meta_valid[datatype].match(self.meta[datatype]))
          else:
              return datatype in Dap._optional_metf _isvalid(self, datatype):
          '''Checks if the given datatype is valid in meta'''
          if datatype in self.meta:
              return bool(Dap._meta_valid[datatype].match(self.meta[datatype]))
          else:
              return datatype in Dap._optional_meta
docs: Checks if the given datatype is valid in meta