This code snippet appears to use **Polars**, a DataFrame library...

This code snippet appears to use Polars, a DataFrame library for Python, and defines a constant or a literal column (datetonull). The code achieves the following steps:

1. Create a literal string using pl.lit('01Jan1900: 00:00:00'):

   • This creates a Polars scalar literal with the string value '01Jan1900: 00:00:00'.

2. Parse the string as a datetime with .str.strptime('%d%b%Y:%H:%M:%S.%f'):

   • The method .str.strptime(pattern) tells Polars to interpret the string as a datetime in the format specified: '%d%b%Y:%H:%M:%S.%f'.
     • %d is the day of the month (e.g., 01).
     • %b is the abbreviated month name (e.g., Jan).
     • %Y is the 4-digit year (e.g., 1900).
     • %H:%M:%S specifies the hour, minute, and second (e.g., 00:00:00).
     • .%f expects fractional seconds, but since the string includes no fractional seconds, it will assume .000000.

3. Cast the result to a pl.Datetime type with .cast(pl.Datetime):

   • The parsed datetime is explicitly converted to the Polars Datetime data type.

Final Outcome:

• This code converts the string '01Jan1900: 00:00:00' into a Polars Datetime object with a value of 1900-01-01 00:00:00.
• The datetonull variable will hold this literal value as a Polars Datetime.