"we create graphs of the current version"
"we can't upgrade from 0.1.1 to 1.5.0, on the fly"
"we can't upgrade from 0.1.1 to 1.5.0, explicitly"
"we can't upgrade from 0.2 to 1.5.0, on the fly"
"we can upgrade from 0.2 to 1.5.0, explicitly"
"we can't upgrade from 0.5 to 1.5.0, on the fly"
"we can upgrade from 0.5 to 1.5.0, explicitly"
"we can't upgrade from 0.6 to 1.5.0, on the fly"
"we can upgrade from 0.6 to 1.5.0, explicitly"
"we can upgrade from 1.0.0 to 1.5.0, on the fly"
"we can upgrade from 1.0.0 to 1.5.0, explicitly"
"igraph_version returns a version string"

we can upgrade from 0.2 to 1.5.0, explicitly

we can upgrade from 0.5 to 1.5.0, explicitly

we can upgrade from 0.6 to 1.5.0, explicitly