  We explain how a generic HKT geometry can be derived using the language of N
= 4 supersymmetric quantum mechanics. To this end, one should consider a
Lagrangian involving several (4,4,0) multiplets defined in harmonic superspace
and subject to nontrivial harmonic constraints. Conjecturally, this general
construction worked out earlier by Delduc and Ivanov gives a complete
classification of all HKT geometries. Each such geometry is generated by two
different functions (potentials) of a special type that depend on harmonic
superfields and on harmonics.
  Given these two potentials, one can derive the vielbeins, metric, connections
and curvatures, but this is not so simple: one should solve rather complicated
differential equations. We illustrate the general construction by giving a
detailed derivation of the metric for the hyper-Kaehler Taub-NUT manifold. In
the generic case, we arrive at an HKT geometry. In this paper, we give a simple
proof of this assertion.
