docstr: Read value from mutable tensor with a synchronous API.
  
  Parameters
  ----------
  index:
      Index to read from the tensor.
docstr_tok: ["Read","value","from","mutable","tensor","with","a","synchronous","API",".","Parameters","--","--","--","--","--","index",":","Index","to","read","from","the","tensor","."]
code: def __getitem__(self, index):
      """
      Read value from mutable tensor with a synchronous API.
  
      Parameters
      ----------
      index:
          Index to read from the tensor.
      """
      coro = self.read(index)
      fut = asyncio.run_coroutine_threadsafe(coro, self._loop)
      return fut.result()
  
file_path: mars/mars/services/mutable/core.py
imports: import asyncio
label_desc: Use image node_id 7 for calling the MutableTensor obj's underlying member method code with example usage: obj.__getitem__(index) and returns: fut