MultiLineString cannot be created from a LineString + MultiLineString

[mattijn]

from IPython.display import SVG, display
from topojson.core.extract import Extract
from shapely import geometry
from shapely.ops import linemerge
from shapely.ops import shared_paths

data = [
    {
        "type": "LineString",
        "coordinates": [(0, 0), (10, 0), (10, 5), (20, 5)],
    },
    {
        "type": "LineString",
        "coordinates": [(5, 0), (25, 0), (25, 5), (16, 5), (16, 10), (14, 10), (14, 5), (0, 5)],
    }
]

ex = Extract(data).output
lines = geometry.MultiLineString(ex['linestrings'])
svg_lines = lines._repr_svg_()
svg_lines = svg_lines.replace('stroke="#66cc99"', 'stroke="orange"', 1)
svg_lines = svg_lines.replace('stroke-width="0.54"', 'stroke-width="1.5"', 1)
svg_lines = svg_lines.replace('opacity="0.8"', 'opacity="0.4"', 1)

display(SVG(svg_lines))

g1 = ex['linestrings'][0]
g2 = ex['linestrings'][1]

fw, bw = shared_paths(g1, g2)

linemerge(fw)

linemerge(bw)

geometry.MultiLineString([linemerge(fw), linemerge(bw)])

---------------------------------------------------------------------------

NotImplementedError                       Traceback (most recent call last)

<ipython-input-8-7691d6f56d9d> in <module>
----> 1 geometry.MultiLineString([linemerge(fw), linemerge(bw)])


~/miniconda3/lib/python3.7/site-packages/shapely/geometry/multilinestring.py in __init__(self, lines)
     50             pass
     51         else:
---> 52             self._geom, self._ndim = geos_multilinestring_from_py(lines)
     53 
     54     def shape_factory(self, *args):


~/miniconda3/lib/python3.7/site-packages/shapely/geometry/multilinestring.py in geos_multilinestring_from_py(ob)
    132     # add to coordinate sequence
    133     for l in range(L):
--> 134         geom, ndims = linestring.geos_linestring_from_py(obs[l])
    135         subs[l] = cast(geom, c_void_p)
    136 


~/miniconda3/lib/python3.7/site-packages/shapely/speedups/_speedups.pyx in shapely.speedups._speedups.geos_linestring_from_py()


~/miniconda3/lib/python3.7/site-packages/shapely/geometry/base.py in __array_interface__(self)
    792     def __array_interface__(self):
    793         """Provide the Numpy array protocol."""
--> 794         raise NotImplementedError("Multi-part geometries do not themselves "
    795                                   "provide the array interface")
    796 


NotImplementedError: Multi-part geometries do not themselves provide the array interface