You are given a dictionary sensors keyed by sensor id (string). Each value is a record {'readings': list[int]} where readings is a non-empty list of integer measurements.
Return a new dictionary mapping each sensor id to a summary record {'total': <sum of readings>, 'max': <largest reading>, 'count': <number of readings>}. The returned dictionary must be built in ascending order of sensor id. If sensors is empty, return an empty dictionary.
NOTE: This is a function-type question — you only write the function. Do not read input or print anything; a hidden checker calls your function and checks its return value.
Arguments
{'s1': {'readings': [1, 2, 3]}, 's2': {'readings': [10, 5]}}
Returns
{'s1': {'total': 6, 'max': 3, 'count': 3}, 's2': {'total': 15, 'max': 10, 'count': 2}}