einx: Universal Notation for Tensor Operations

einx is a Python library that provides a universal interface to formulate tensor operations in frameworks such as Numpy, PyTorch, Jax, Tensorflow, and MLX, using an Einstein-inspired notation. It offers a streamlined approach to complex tensor manipulations, often by compiling operations to backend-specific function calls, which helps minimize overhead. The current version is 0.4.3, with frequent minor releases addressing fixes and adding support for new backends.