'Set the epsilon for picking used by this artist
*picker* can be one of the following:
* *None*: picking is disabled for this artist (default)
* A boolean: if *True* then picking will be enabled and the
artist will fire a pick event if the mouse event is over
the artist
* A float: if picker is a number it is interpreted as an
epsilon tolerance in points and the artist will fire
off an event if it\'s data is within epsilon of the mouse
event.  For some artists like lines and patch collections,
the artist may provide additional data to the pick event
that is generated, e.g., the indices of the data within
epsilon of the pick event
* A function: if picker is callable, it is a user supplied
function which determines whether the artist is hit by the
mouse event::
hit, props = picker(artist, mouseevent)
to determine the hit test.  if the mouse event is over the
artist, return *hit=True* and props is a dictionary of
properties you want added to the PickEvent attributes.
ACCEPTS: [None|float|boolean|callable]'

def set_picker(self, picker):

    self._picker = picker
