code: def parameter_to_field(self, name):
          
          if name not in self._parameters:
              raise ValueError("no '%s' parameter found" % (name))
          if self._fields.count(name) > 0:
              raise ValueError("field with name '%s' already exists" % (name))
  
          data = np.array([self._parameters[name]]*self._num_fix)
  
          self.rm_parameter(name)
          self.add_field(name, data)
docs: Promotes a parameter to a field by creating a new array of same
          size as the other existing fields, filling it with the current
          value of the parameter, and then removing that parameter.