adds pynext

Author: Christopher Doris

docs/src/pythoncall.md

@@ -130,6 +130,7 @@ pyissubclass
 pyisinstance
 pyhash
 pyiter
+pynext
 ```
 
 ### Conversion to Julia

src/abstract/iter.jl

@@ -6,6 +6,14 @@ Equivalent to `iter(x)` in Python.
 pyiter(x) = pynew(errcheck(@autopy x C.PyObject_GetIter(getptr(x_))))
 export pyiter
 
+"""
+    pynext(x)
+
+Equivalent to `next(x)` in Python.
+"""
+pynext(x) = pybuiltins.next(x)
+export pynext
+
 """
     unsafe_pynext(x)