Builds the proper search syntax (query) for Landsat theia API

def _query_builder(self,
                       start_date=None,
                       end_date=None,
                       clipper=None
                        ):
        """ Builds the proper search syntax (query) for Landsat theia API """
        search_string='format=json&lang=fr&q='
        if (start_date is not None):
            if(end_date is not None):
                search_string+='entre+'+start_date+'+et+'+end_date
            else:
                search_string+=start_date
        elif(end_date is not None): 
            search_string+=end_date
        
        if(clipper.query is not None):
            query=clipper.query.replace(' ','+')
            search_string+='+'+query
        if(clipper.bbox is not None):
            search_string+='&box='+clipper.bbox

        return search_string