spanner_markers
spanner_markers(text: str, side: str)The start and end marker labels of a spanner: text with an opening bracket before it and a closing bracket after it, the brackets’ shape saying which side of the line the spanner sits on ("above" or "below").
>>> spanner_markers("slur", "above"), spanner_markers("verse 1", "below")
(('⌈slur', 'slur⌉'), ('⌊verse 1', 'verse 1⌋'))