tanaka: Design Shaded Contour Lines (or Tanaka) Maps

#' @title Tanaka Contours Package
#' @name tanaka-package
#' @rdname tanaka-package
#' @description
#' The tanaka package is a simplified implementation of the Tanaka method.
#' Also called "relief contours method", "illuminated contour method", or
#' "shaded contour lines method", the Tanaka method enhances the representation
#' of topography on a map using shaded contour lines. North-west white contours
#' represent illuminated topography and south-east black contours represent
#' shaded topography.
#' @docType package
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