code: def test_dodge2_preserve_single_interval():
      n = 3
      data = pd.DataFrame({"x": range(1, n + 1), "y": range(1, n + 1)})
  
      p = ggplot(
          data, aes(xmin="x-.45", xmax="x+.45", ymin=0, ymax="y")
      ) + geom_rect(position=position_dodge2(preserve="single"))
      assert p == "dodge2_preserve_single_interval"
  
imports: import string
  import numpy
  import pandas
  import pytest
  from plotnine import aes, after_stat, geom_bar, geom_boxplot, geom_col, geom_jitter, geom_point, geom_rect, geom_segment, geom_text, ggplot, position_dodge, position_dodge2, position_jitter, position_jitterdodge, position_nudge, position_stack, scale_y_log10, stage
  from plotnine.exceptions import PlotnineError
  from plotnine.positions.position import position
label_desc: Use image node_id 13 for calling a global function with example usage: test_dodge2_preserve_single_interval() without return types