// Verifies that null elements in the symbols list declare unknown symbol text (“gaps”) for its SID within the sequence,
// and that any element of the list that is not a string must be interpreted as if it were null.
embedded_documents::[
"s1 s2 s3",
'''$ion_symbol_table::{'''
''' symbols:["s1", "s2", null.string, "s3"]'''
'''}'''
'''$10 $11 $13''',
'''$ion_symbol_table::{'''
''' symbols:[42, "s1", "s2", "s3"]'''
'''}'''
'''$11 $12 $13''',
'''$ion_symbol_table::{'''
''' symbols:["s1", $3, "s2", null, "s3", 123.4e5],'''
''' imports:[ {name: "foo", version: 1, max_id: 10} ]'''
'''}'''
'''$20 $22 $24'''
]