Definition : A group $G$ is said to have a finite rank $r$ if every finitely generated subgroup can be generated by $r$ elements, and $r$ is the least positive integer with this property. If no such integer exists, then we say that $G$ has an infinite rank.
In László Fuchs' book "Abelian Groups 2015," Chapter 13 discusses torsion-free groups of infinite rank. Fuchs mentions an indecomposable group of rank aleph-null in this chapter. Can you provide insights into the properties and structure of this particular indecomposable group as described by Fuchs?