%load_ext cythonmagic

%%cython --annotate
from libc.stdlib cimport strtol as _strtol

def strtol(bytes n, int base=10):
    cdef int ret
    cdef char *nptr = n
    cdef char *endptr
    ret = _strtol(nptr, &endptr, base)
    if endptr == nptr or endptr[0] != 0:
        raise ValueError("Invalid string %r at at character %d" % (n, endptr-nptr+1))
    return ret

strtol('hello', base=36)

%timeit strtol('hello', base=36)