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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_crm_leader(resource, retry=False):
 """ Returns True if the charm calling this is the elected corosync leader, as returned by calling the external "crm" command. We allow this operation to be retried to avoid the possibility of getting a false negative. See LP #1396246 for more info. """

    if resource == DC_RESOURCE_NAME:
        return is_crm_dc()
    cmd = ['crm', 'resource', 'show', resource]
    try:
        status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
        if not isinstance(status, six.text_type):
            status = six.text_type(status, "utf-8")
    except subprocess.CalledProcessError:
        status = None

    if status and get_unit_hostname() in status:
        return True

    if status and "resource %s is NOT running" % (resource) in status:
        raise CRMResourceNotFound("CRM resource %s not found" % (resource))

    return False