Fabfile sample using require function

fabfile.py

from fabric.api import *

def is_local():
    if env.host  == 'localhost':
        env.lrun = local
    else:
        env.lrun = run

    print('host %(host)s using function %(lrun)s' % env)

def host_type():
    require('lrun', provided_by=is_local)
    env.lrun('uname -s')