docs: def field(self, well_x=1, well_y=1, field_x=1, field_y=1):
          """ScanFieldData of specified field.
  
          Parameters
          ----------
          well_x : int
          well_y : int
          field_x : int
          field_y : int
  
          Returns
          -------
          lxml.objectify.ObjectifiedElement
              ScanFieldArray/ScanFieldData element.
          """
          xpath = './ScanFieldArray/ScanFieldData'
          xpath += _xpath_attrib('WellX', well_x)
          xpath += _xpath_attrib('WellY', well_y)
          xpath += _xpath_attrib('FieldX', field_x)
          xpath += _xpath_attrib('FieldY', field_y)
          # assume we find only one
          return self.root.find(xpath)