If 'e' is a tree of commas, returns the leftmost expression by stripping off it from the tree. The remained part of the tree is returned via *pe0. Otherwise 'e' is directly returned and *pe0 is set to NULL.
See Implementation
If 'e' is a tree of commas, returns the leftmost expression by stripping off it from the tree. The remained part of the tree is returned via *pe0. Otherwise 'e' is directly returned and *pe0 is set to NULL.