This function evaluate a left value. A left value is a special expression that value can be assigned, and therefore they usually stand on the left side of the assignment operator. That is the reason for the name.
When an expression is evaluates a pointer to a memory object is returned. Whenever a left value is evaluated a pointer
to the variable is returned. If any code assignes value to the variable pointed by the return value of this function
it should release the memory object that the left value points currently.
pFixSizeMemoryObject *execute_LeftValue(pExecuteObject pEo,
unsigned long lExpressionRootNode,
pMortalList pMyMortal,
int *piErrorCode,
int iArrayAccepted
){