Partition each element in a around sep.
Calls str.partition element-wise.
For each element in a, split the element as the first occurrence of sep, and return 3 strings containing the part before the separator, the separator itself, and the part after the separator. If the separator is not found, return 3 strings containing the string itself, followed by two empty strings.
| Parameters : | a : array_like, {str, unicode} 
 sep : {str, unicode} 
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| Returns : | out : ndarray, {str, unicode} 
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See also