code: def _position_for_aspirate(self, location=None, clearance=1.0):
          
  
          placeable = None
          if location:
              placeable, _ = unpack_location(location)
              # go to top of source, if not already there
              if placeable != self.previous_placeable:
                  self.move_to(placeable.top())
          else:
              placeable = self.previous_placeable
  
          # if pipette is currently empty, ensure the plunger is at "bottom"
          if self.current_volume == 0:
              pos, _, _ = pose_tracker.absolute(
                  self.robot.poses, self.instrument_actuator)
              if pos != self._get_plunger_position('bottom'):
                  # move to top of well to avoid touching liquid
                  if placeable:
                      self.move_to(placeable.top())
                  self.instrument_actuator.set_active_current(
                      self._plunger_current)
                  self.robot.poses = self.instrument_actuator.move(
                      self.robot.poses,
                      x=self._get_plunger_position('bottom')
                  )
  
          # then go inside the location
          if location:
              if isinstance(location, Placeable):
                  location = location.bottom(min(location.z_size(), clearance))
              self.move_to(location, strategy='direct')
docs: Position this :any:`Pipette` for an aspiration,
          given it's current state