The editor is responsible for assembling the audio and visual elements into the final film. Although their primary role is during the post-production phase, they will also play an important role in the pre-production and production phases. Editors should consider pacing and narrative rhythm, the creation of tension and mood, as well as editing styles (continuity or montage) and transitions (straight cuts, dissolves, fades in and fades out) in terms of narrative purpose. Some genre/films may require additional techniques such as keying, masking, double exposure, advanced titling, subtitles, colouring, animation and special effects.