ndi.fun.ensemble.findExisting

  ndi.fun.ensemble.findExisting - find the ensemble map documents of an ensemble element

  DOCS = ndi.fun.ensemble.FINDEXISTING(S, ENSEMBLEELEMENT, ...)

  Returns the 'ensemble' map documents that belong to ENSEMBLEELEMENT (an
  ndi.element.ensemble object or its element document id) in the ndi.session (or
  ndi.dataset) S. Optionally restrict to a single epoch. DOCS is a cell array of
  the matching ndi.document objects (empty if none).

  This is used by ndi.fun.ensemble.create and ndi.fun.ensemble.allElement to
  detect whether an ensemble already exists for a given element and epoch.

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  OPTIONS (name/value pairs)
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    epochid ('')  - if non-empty, return only the map document for this epoch.

  See also: ndi.fun.ensemble.create, ndi.element.ensemble