I am iterating a `boost interval_set<unsigned_int>`, and I was expecting each iterator to be a `boost interval`, whose values would be accessed with the `upper` and `lower` methods:

```
boost::icl::interval_set<unsigned int> outages;
// ...
// Insert intervals into the database
for(boost::icl::interval_set<unsigned int>::iterator it =
    outages.begin(); it != outages.end(); it++){

    DATA_ACQUISITION::InsertInterval(db, it->lower(),
        it->upper())
}

```

But I am receiving errors at both `lower` and `upper` methods: **Method ... could not be resolved**, which suggests me that the iterator is not pointing to an `interval` at all.

So, what am I really iterating here? How to iterate though the `intervals` inserted into the `interval`\_set?

EDIT: Adding SSCCE:

```
#include <boost/icl/interval_set.hpp>
#include <iostream>
#include <vector>

int main() {
    boost::icl::interval_set<unsigned int> outages;
    for(unsigned int i=0; i<5; i++){
        outages += boost::icl::discrete_interval<unsigned int>::closed(
            (i*10), ((i*10) + 5));
    }

    for(boost::icl::interval_set<unsigned int>::iterator it =
        outages.begin(); it != outages.end(); it++){

        std::cout << it->lower() << boost::icl::upper(*it);
    }
    return 0;
}

```

Additional info:

* I am currently not adding any library ti the linker (until now, no error suggested I needed that, and haven't found which argument should I add to the -l anyway)
	+ Compiler g++ 4.8.1
	+ Boost version: 1.46