def sniff_params(read):
    """
    Given a read dict parsed from JSON, compute a mapping parameter dict for the read.
    
    The read will have param_XXX annotations. Turn those into a dict from XXX to value.
    
    These should be the same for every read.
    """
    
    # This is the annotation dict from the read
    annot = read.get('annotation', {})
    
    # This is the params dict to fill in
    params = {}
    
    for annot_name in annot.keys():
        if annot_name.startswith('param_'):
            # Split the param annotations on underscore
            (_, param_name) = annot_name.split('_')
            
            # Save the values under the name
            params[param_name] = annot[annot_name]
    
    return params