@spiceErrorCheck<EOL>def pos(string, substr, start):
string = stypes.stringToCharP(string)<EOL>substr = stypes.stringToCharP(substr)<EOL>start = ctypes.c_int(start)<EOL>return libspice.pos_c(string, substr, start)<EOL>
Find the first occurrence in a string of a substring, starting at
a specified location, searching forward.

http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/pos_c.html

:param string: Any character string.
:type string: str
:param substr: Substring to locate in the character string.
:type substr: str
:param start: Position to begin looking for substr in string.
:type start: int
:return:
        The index of the first occurrence of substr
        in string at or following index start.
:rtype: int