code: def asarray(self):
  		
  		# most codes don't use this feature, this is the only place
  		# numpy is used here, and importing numpy can be
  		# time-consuming, so we derfer the import until needed.
  		import numpy
  		try:
  			dtype = ligolwtypes.ToNumPyType[self.Type]
  		except KeyError as e:
  			raise TypeError("cannot determine numpy dtype for Column '%s': %s" % (self.getAttribute("Name"), e))
  		return numpy.fromiter(self, dtype = dtype)
docs: Construct a numpy array from this column.  Note that this
  		creates a copy of the data, so modifications made to the
  		array will *not* be recorded in the original document.