docs: def op_symbol(op_node):
      """Get the GLSL symbol for a Python operator."""
      ops = {
          # TODO(nicholasbishop): other unary ops
          ast.UAdd: '+',
          ast.USub: '-',
  
          # TODO(nicholasbishop): FloorDiv, Pow, LShift, RShift,
          # BitOr, BitXor, BitAnd
          ast.Add: '+',
          ast.Sub: '-',
          ast.Mult: '*',
          ast.Div: '/',
          ast.Mod: '%',
  
          # Comparison
          ast.Eq: '=',
          ast.NotEq: '!=',
          ast.Lt: '<',
          ast.LtE: '<=',
          ast.Gt: '>',
          ast.GtE: '>=',
      }
      # Python3 matrix multiplication
      if hasattr(ast, 'MatMult'):
          ops[ast.MatMult] = '*'
      return ops[op_node.__class__]