Non–parametric fitting of slow–rotator sequence of Pleiades. Top panel: color–period diagram; the empirical constraints on slow–rotator sequence extracted from non-parametric fit are shown as empty red squares with error bars. Bottom left: normalized fit residuals; grey dashed lines represent deviations of ±2.5 × σ from mean. Bottom right: cumulative distribution of normalized fit residuals compared with that of normal distribution.