get_stationary: Get near-stationary states
In QinglongYan/ANSSI: Automated near-stationary state identifier

This function is applied to identify near-stationary states from candidate intervals based on the modified Cassidy's method

1 2	get_stationary(datasets, not = 0.2, hot = 0.4, xot = 0.6, ndr = NULL, hdr = NULL, xdr = NULL, gapt, relation)

`datasets`	The candidate intervals in list format
`not`	Normal occupancy threshold (0.2 by default)
`hot`	High occupancy threshold (0.4 by default)
`xot`	Extremely high occupancy threshold (0.6 by default)
`ndr`	The minimum acceptable duration in normal-occupancy periods (10 by default)
`hdr`	The minimum acceptable duration in high-occupancy periods (4 by default)
`xdr`	The minimum acceptable duration in extremely high-occupancy periods (2.5 by default)
`gapt`	Gap threshold
`relation`	Duration-occupancy relations; optional choices are "stepwise", "linear", "polynomial", and "unitgap"