R/human-SIP-dts.R
    dts_lines_X_SIP_dts.RdAdd lines for the density of infected individuals for the SIP_dts model
dts_lines_X_SIP_dts(
  XH,
  pars,
  clrs = c("darkblue", "darkred", "darkgreen"),
  llty = 1
)a list with the outputs of parse_dts_out_X.SIP_dts
a list that defines an ramp.dts model (e.g.,  generated by dts_setup())
a vector of colors
an integer (or integers) to set the lty for plotting