What poetic techniques Dickinson uses in her poem " I heard a Fly buzz -when I died- ?

Like the buzzing of a fly, the rhythm of Emily Dickinson's
poem, "I heard a Fly buzz--when I died--" is interrupted by dashes.  In this poem,
Dickinson uses her formal pattern of iambic tetrameter and trimeter.  Each stanza has an
abab pattern; the first three stanzas are written in half rhymes
[e.g. Room/Storm, firm/Room, be/Fly] while the final stanza is
written in full rhyme with me/see. With the half rhyme and dashes,
there is a sense of incompletion, while only in the last stanza with the death of the
speaker is there completion.

In this deathbed scene,
another of the images of domestic life about which Dickinson writes, the fly intrudes at
the most poignant of all human occurrences.  At the last moment of death as the speaker
wishes to be spiritually prepared for her death, "when the King/Be witnessed--in the
Room--" instead the fly, a metaphor for the intrusion of something so trivial and
annoying, interrupts her final moments as she "could not see to see--" and the solemn
moments of the onlookers, characterized by synedoche [Eyes,
Breaths] who "were gathering firm" are interrupted as
well.