<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_mimetype(mimedb, mimetype, extension):
 """Add or replace a mimetype to be used with the given extension."""

    # If extension is already a common type, strict=True must be used.
    strict = extension in mimedb.types_map[True]
    mimedb.add_type(mimetype, extension, strict=strict)