Table: canada_street_railways
Columns: name_of_system
location
traction_type
date_from
date_to

Question: What is the date (to) associated wiht a traction type of electric and the Yarmouth Light and Power Company system?
SQL: SELECT "date_to" FROM canada_street_railways WHERE "traction_type" = 'electric' AND "name_of_system" = 'yarmouth light and power company'