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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build(ctx, builder="html", options=""):
 """Build docs with sphinx-build"""

    sourcedir = ctx.config.sphinx.sourcedir
    destdir = Path(ctx.config.sphinx.destdir or "build")/builder
    destdir = destdir.abspath()
    with cd(sourcedir):
        destdir_relative = Path(".").relpathto(destdir)
        command = "sphinx-build {opts} -b {builder} {sourcedir} {destdir}" \
                    .format(builder=builder, sourcedir=".",
                            destdir=destdir_relative, opts=options)
        ctx.run(command)