hasNext is a generic function that indicates if the iterator
has another element.
Usage
hasNext(obj, ...)
## S3 method for class 'iload.molecules':
hasNext(obj, \dots)
Arguments
obj
an iterator object.
...
additional arguments that are ignored.
Value
Logical value indicating whether the iterator has a next element. In the context
of reading a structure file, this indicates whether there are more molecules to read