There were two functions for getting gas-mixes at a certain timestamp:
- get_gasmix() for repeated queries.
- get_gas_at_time() for a single query.
Since the latter is a special case of the former, simply call
the former in the latter. Moreover, rename to get_gasmix_at_time()
for consistency.
Replace on get_gasmix() call, which was outside of a loop by the
corresponding get_gasmix_at_time() call.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>