Flattens a single sublist at a specified position.
FlattenAt[list, n]
FlattenAt[expr, {i, j, …}]
FlattenAt[expr, {{i1, j1, …}, {i2, j2, …}, …}]
FlattenAt[pos]
FlattenAt[{1, {2, 3}, 4, {5, 6}}, 2]
→ {1, 2, 3, 4, {5, 6}}FlattenAt[{a, {b, c}, {d, e}, {f}}, -1]
→ {a, {b, c}, {d, e}, f}FlattenAt[{a, {b, c}, {d, e}, {f}}, {{2}, {4}}]
→ {a, b, c, {d, e}, f}FlattenAt[{a, {{b, c}, {d, e}}, {f}}, {2, 1}]
→ {a, {b, c, {d, e}}, {f}}FlattenAt[2][{a, {b, c}, {d, e}, {f}}]
→ {a, b, c, {d, e}, {f}}