code: def test_line_merge_directed():
      lines = MultiLineString([[(0, 0), (1, 0)], [(0, 0), (3, 0)]])
      # Merge lines without directed, this requires changing the vertex ordering
      result = shapely.line_merge(lines)
      assert_geometries_equal(
          result, LineString([(1, 0), (0, 0), (3, 0)])
      )
      # Since the lines can't be merged when directed is specified
      # the original geometry is returned
      result = shapely.line_merge(lines, directed=True)
      assert_geometries_equal(result, lines)
  
imports: import numpy
  import pytest
  import shapely
  from shapely import GeometryCollection, LinearRing, LineString, MultiLineString, Point
  from shapely.errors import UnsupportedGEOSVersionError
  from shapely.testing import assert_geometries_equal
  from shapely.tests.common import empty_line_string, empty_point, line_string, linear_ring, multi_line_string, multi_point, multi_polygon, point, polygon
label_desc: Use image node_id 14 for calling a global function with example usage: test_line_merge_directed() without return types