from typing import Tuple


def beta_mode_concentration_from_a_b(a: float, b: float) -> Tuple[float, float]:
	"""
	Computes the mode and concentration of a beta distribution from its shape parameters, alpha and beta.

	Parameters
	----------
	a : float
		alpha parameter
	b : float
		beta parameter

	Returns
	-------
	out: tuple of floats
		Mode and concentration

	"""

	assert a > 1 and b > 1
	return (a - 1.) / (a + b - 2.), a + b