from neovim import attach

nvim = attach('child', argv=["/bin/env","nvim","--embed"])
buffer = nvim.current.buffer
buffer[0] = 'visual mode'
nvim.feedkeys("fmve")
print("Current caret position: {}".format(nvim.windows[0].cursor))
cmd ='getpos("'<")'
print("Start of visual selection: {}".format(nvim.eval(cmd)))

Current caret position: [1,10]
Start of visual selection: [0,0,0,0]

Start of visual selection: [1,8,1,11]