[RTW47]

then I use Eval() function:

import vapoursynth as vs
core = vs.get_core()
core.std.LoadPlugin(r'C:\Program Files\VapourSynth\filters\vsavsreader.dll')
avs = """
LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\LSMASHSource.dll")
LWLibavVideoSource("D:\amv\10bit.mp4", format="YUV420P8")
#ConvertToRGB24(matrix = "Rec709")
"""
video = core.avsr.Eval(lines = avs)
video.set_output()

In Python shell I get this:

Python 3.3.2 (v3.3.2:d047928ae3f6, May 16 2013, 00:03:43) [MSC v.1600 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>> 
Traceback (most recent call last):
  File "C:\Users\Edgaras\Desktop\py\1_vsavsreader # 'Eval' Libav FAIL.py", line 9, in <module>
    video = core.avsr.Eval(lines = avs)
  File "vapoursynth.pyx", line 983, in vapoursynth.Function.__call__ (src\cython\vapoursynth.c:15542)
vapoursynth.Error: 'Eval: 
failed to invoke \nLoadPlugin("C:\\Program Files\\AviSynth 2.5\\plugins\\LSMASHSource.dll")
\nLWLibavVideoSource("D:\x07mv\x08bit.mp4", format="YUV420P8")\n#ConvertToRGB24(matrix = "Rec709")\n'
>>>

then importing same .avs script(s) using vsavsreader's Import() function, then there's no error.

-vapoursynth r20 RC3
-avisynth 2.6 alpha 5
-vsavsreader 0.1.0