Function parse_smpte_string 

pub fn parse_smpte_string(
    s: &str,
    rate: FrameRate,
) -> Result<Timecode, TimecodeError>

Parses a SMPTE timecode string like “01:02:03:04” or “01:02:03;04”.

The separator between seconds and frames determines drop-frame vs non-drop:

• : for non-drop frame
• ; for drop frame

Errors

Returns an error if the string format is invalid.