Directory Listing with size (no sub folders) via Python 01

PS E:\> python pythonscript1
C:\Users\Owner\AppData\Local\Programs\Python\Python36\python.exe: can't open file 'pythonscript1': [Errno 2] No such file or directory
PS E:\> python pythonscript1.py
  File "pythonscript1.py", line 10
    print get_size()
                 ^
SyntaxError: invalid syntax
PS E:\>