Returns an arrow for a chart. Params: the text, xloc and yloc are
		coordinates to position the arrow. Orientation is the way to display
		the arrow: possible values are ``[<, ^, >, v]``. Arrow style is the
		graphic style of the arrow: 
		possible values: ``[-, ->, -[, -|>, <->, <|-|>]``

def arrow_(self, xloc, yloc, text, orientation="v", arrowstyle='->'):
		"""
		Returns an arrow for a chart. Params: the text, xloc and yloc are
		coordinates to position the arrow. Orientation is the way to display
		the arrow: possible values are ``[<, ^, >, v]``. Arrow style is the
		graphic style of the arrow: 
		possible values: ``[-, ->, -[, -|>, <->, <|-|>]``
		"""
		try:
			arrow = hv.Arrow(
				xloc,
				yloc,
				text,
				orientation,
				arrowstyle=arrowstyle)
			return arrow
		except Exception as e:
			self.err(e, self.arrow_, "Can not draw arrow chart")