<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def guard_prepublish(analysis_request):
 """Returns whether 'prepublish' transition can be perform or not. Returns True if the analysis request has at least one analysis in 'verified' or in 'to_be_verified' status. Otherwise, return False """

    valid_states = ['verified', 'to_be_verified']
    for analysis in analysis_request.getAnalyses():
        analysis = api.get_object(analysis)
        if api.get_workflow_status_of(analysis) in valid_states:
            return True
    return False