code: def to(self, unit):
          
          if not _has_astropy:
              raise ImportError("astropy must be installed for unit/quantity support")
  
          if self.unit is None:
              raise ValueError("no units currently set")
  
          if not is_unit_or_unitstring(unit)[0]:
              raise ValueError("unit not recognized")
  
          mult_factor = self.unit.to(unit)
          copy = self.copy() * mult_factor
          copy.unit = unit
          return copy
docs: convert between units.  Returns a new nparray object with the new units