sentences: cat is when electromagnetic heart forms light and sound matter
docs: heart_sound is sound_emission. cats is musical. heartbeat is force. heart_murmur is heart_sound. sound_of_heartbeating is audible_beat. animal_noise is audible_sound. sound_of_heartbeating is audible_sound. purr is sound. animal_utterance is audible_sound. electromagnetism is fundamental_force_of_universe.