Documentation for method is-leap-year assembled from the following pages:

Role: Dateish §

From Dateish

(Dateish) method is-leap-year §

Defined as:

method is-leap-year(Dateish:D: --> Bool:D)

Returns True if the year of the Dateish object is a leap year.

say DateTime.new(:year<2016>).is-leap-year; # OUTPUT: «True␤» 
say Date.new("1900-01-01").is-leap-year;    # OUTPUT: «False␤»