Linters and helpers

Your friend has run some code through a linter. They've sent you the output to ask some questions, but forgot to mention what tool they used. Here it is:

task.py:1:1: F401 'some_module' imported but unused
import some_module
^
task.py:3:1: E302 expected 2 blank lines, found 1
def function(a, b):
^
task.py:4:13: E225 missing whitespace around operator
    return a>b

Which command did your friend use?