Ruby - Not sure of syntax for invoking a function
===

I am in the ruby console, and I am trying to invoke a method and I am not getting the syntax right.

Here is the structure of the file:

    module App
      module Tools
        module Pollers
          class Kpi
            attr_reader :start_time,:stop_time
    
            def initialize(start_time,stop_time)
              @start_time = start_time
              @stop_time = stop_time
            end
            .....

and I am trying to invoke this in the console like this:

    ?> kpi = App::Tools::Pollers::Kpi.initialize(start,end_date)
    SyntaxError: compile error
    (irb):17: syntax error, unexpected tCONSTANT, expecting kDO or '{' or '('

Would someone be able to point me to the right syntax for invoking the initialize ?

Thanks!