imap_processing.spice.time.str_yyyymmdd_to_ttj2000ns# imap_processing.spice.time.str_yyyymmdd_to_ttj2000ns(date_str: str) → int64# Convert a YYYYMMDD date string to TTJ2000 nanoseconds. Parameters: date_str (str) – The date string in YYYYMMDD format. Returns: The corresponding time in TTJ2000 nanoseconds. Return type: int