There are two python modules named 'magic' that do the same thing, but with incompatible APIs. One of these ships with libmagic, and (this one) is distributed through pypi. Both have been around for many years and have substantial user bases. This incompatibility is a major source of pain for users, and bug reports for me.
To mitigate this pain, python-magic has added a compatibility layer to export the libmagic python API parallel to the existing one.
The mapping between the libmagic and python-magic functions is:
detect_from_filename => from_file
detect_from_content => from_buffer
detect_from_fobj => from_descriptor(f.fileno())
open => Magic()