Beginner's question - class definition

[banksam at swanhill.net.au]

Can anyone explain please why the following definition ( from the
Python documentation)

class Complex:
	def _init_(self, realpart, imagpart):
		self.r = realpart
		self.i = imagpart

when followed by the following attempt to create an instance

x = Complex(3.0,-4.5)

gives this error message

Traceback (innermost last):
  File "<pyshell#5>", line 1, in ?
    x = Complex(3.0,-4.5)
TypeError: this constructor takes no arguments

So far I have had the same error message from any similar definitions
taken from other tutorials.  I am clearly doing something wrong, but I
don't know what.

Arthur Banks