Python:Extra string functions: before, after, between

"""
strlib.py
"""
 
def after(s,pat):
    #returns the substring after pat in s.
    #if pat is not in s, then return a null string!
    pos =s.find(pat)
    if pos != -1:
       return s[pos+len(pat):]
    return ""
 
 
def rafter(s,pat):
    #returns the substring after pat in s.
    #if pat is not in s, then return a null string!
    pos =s.rfind(pat)
    if pos != -1:
       return s[pos+len(pat):]
    return ""
 
 
def before(s, pat):
    #returns the substring before pat in s.
    #if pat is not in s, then return a null string!
    pos =s.find(pat)
    if pos != -1:
       return s[:pos]
    return ""
 
 
def rbefore(s, pat):
    #returns the substring before pat in s.
    #if pat is not in s, then return a null string!
    pos =s.rfind(pat)
    if pos != -1:
       return s[pos+len(pat):]
    return ""
 
 
def between(s, bpat, apat):
    # returns substring between bpat and apat in s.
    # if bpat or apat is not in s, then return a null string.
    start = s.find(bpat)
    if start != -1:
       end = s[start+len(bpat):].find(apat)
       if end != -1:
          return s[start+len(bpat):start+len(bpat)+end] 
       return ""
    return ""
 
def rbetween(s, bpat, apat):
    # returns substring between bpat and apat in s.
    # if bpat or apat is not in s, then return a null string.
    end  = s.rfind(apat)
    if end != -1:
       before= s[:end].rfind(bpat)
       if before != -1:
          return s[before+len(bpat):end] 
       return ""
    return ""
 
 
if __name__ == "__main__":
   s = '<a href="the quick brown fox">test1</a><a href="jumps over">test2</a>'
   print 'input string:\n',s
   print 'before(x, "<a")=',  before(s, "<a")
   print 'rbefore(x, "<a")=',  rbefore(s, "<a")
   print 'after(x, "<a")=',  after(s, "<a")
   print 'rafter(x, "<a")=',  rafter(s, "<a")
 
   print 'before(s, "</a>")=',before(s, "</a>")
   print 'after (s, "\">\")=',  after(s, '">')
   print """rafter (s,  '">\')=""", rafter(s, '">')
   print 'between( s, ">","</a>")=',  between(s,">","</a>")
   print 'rbetween(s, ">","</a>")=', rbetween(s,">","</a>")