def imports_on_separate_lines(logical_line):
    """Imports should usually be on separate lines.

    Okay: import os\\nimport sys
    E401: import sys, os

    Okay: from subprocess import Popen, PIPE
    Okay: from myclas import MyClass
    Okay: from foo.bar.yourclass import YourClass
    Okay: import myclass
    Okay: import foo.bar.yourclass
    """
    line = logical_line
    if line.startswith('import '):
        found = line.find(',')
        if -1 < found and ';' not in line[:found]:
            yield found, 'E401 multiple imports on one line'
