<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def _connect():
    '''
    Return server object used to interact with Jenkins.

    :return: server object used to interact with Jenkins
    '''
    jenkins_url = __salt__['config.get']('jenkins.url') or \
        __salt__['config.get']('jenkins:url') or \
        __salt__['pillar.get']('jenkins.url')

    jenkins_user = __salt__['config.get']('jenkins.user') or \
        __salt__['config.get']('jenkins:user') or \
        __salt__['pillar.get']('jenkins.user')

    jenkins_password = __salt__['config.get']('jenkins.password') or \
        __salt__['config.get']('jenkins:password') or \
        __salt__['pillar.get']('jenkins.password')

    if not jenkins_url:
        raise SaltInvocationError('No Jenkins URL found.')

    return jenkins.Jenkins(jenkins_url,
                           username=jenkins_user,
                           password=jenkins_password)