<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def createInputBuffer(file, encoding):
 """Create a libxml2 input buffer from a Python file """

    ret = libxml2mod.xmlCreateInputBuffer(file, encoding)
    if ret is None:raise treeError('xmlCreateInputBuffer() failed')
    return inputBuffer(_obj=ret)