builds a list of files and returns as a list

def GetFileList(rootPaths, lstXtn, shortNameOnly='Y'):
    """ 
    builds a list of files and returns as a list 
    """
    numFiles = 0    
    opFileList = []
    if type(rootPaths) == str:
        rootPaths = [rootPaths]
    for rootPath in rootPaths:
        for root, dirs, files in os.walk(rootPath):
            #print('found ' + str(len(dirs)) + ' directories')
            for basename in files:
                for xtn in lstXtn:
                    if fnmatch.fnmatch(basename, xtn):
                        filename = os.path.join(root, basename)
                        numFiles = numFiles + 1
                        if shortNameOnly == 'Y':
                            opFileList.append( os.path.basename(filename))
                        else:
                            opFileList.append(filename)
                        
    return sorted(opFileList)